Well Water Wings, you can get twin time here in Tanzania flying Senecas or as a First Officer flying Twin Otters and all that according to your experience and your Nationality for the time being, but if you are looking for a good pay, Caravans are there for you and they are unaccountable in this country, which means single engine turbine time that you have already opposed.
I don't know much about Namibia, so unfortunately i can't help you on that.